What abnormal condition often arises alongside renal agenesis?

Renal agenesis, particularly bilateral renal agenesis, leads to a significant reduction in amniotic fluid production due to the absence of functioning kidneys. As a result, the fetus is at high risk for developing pulmonary hypoplasia, which is a serious condition characterized by underdeveloped lungs. The lungs require sufficient amniotic fluid to develop properly; when there is a decreased volume of amniotic fluid (oligohydramnios), the growth and maturity of the fetal lungs are compromised. Therefore, pulmonary hypoplasia is a direct consequence of renal agenesis and the resultant decrease in amniotic fluid.

In contrast, while increased fetal heart rate, neonatal jaundice, and decreased fetal movement can occur in various clinical scenarios, they do not inherently arise as primary complications specific to renal agenesis. Increased fetal heart rate can be associated with numerous factors, including stress or hypoxia. Neonatal jaundice can occur due to many causes postnatally, and decreased fetal movement may arise from a range of issues that do not specifically correlate with renal agenesis. Thus, pulmonary hypoplasia is the most relevant and significant abnormality linked with this condition.